The present invention relates generally to the art of welding power supplies. More specifically, it relates to welding power supplies that may be run off two types of electric power, such as utility power (or battery power) and generator power.
Welding power supplies receive input power, and provide output power suitable for welding. It is known in the welding arts to provide utility power (230/460, 60 Hz, e.g.) as input power to the welding power supply. (Power supply, as used herein, refers to the circuitry which receives and converts or transforms power, as well as control circuitry and other ancillary circuitry associated therewith). Welding power supplies that receive utility power include phase controlled rectifiers (U.S. Pat. No. 4,038,515, e.g., hereby incorporated by reference), convertors (invertors, series resonant convertors, etc.) and transformers with rectifiers. A convertor-based welding power supply well-suited for utility power is described in U.S. Pat. No. 5,783,799 (hereby incorporated by reference), Series Resonant Converter, And Method And Apparatus For Control Thereof, issued Jul., 21, 1998, and assigned to the assignee of this invention.
Welding power supplies designed for utility power input generally receive a voltage close to the rated voltage (460 V e.g.), or one of a plurality of rated voltages. The current drawn is sufficient to provide the output power desired, When the desired output changes suddenly, the input power needed suddenly changes, and utility power is able to quickly respond. Welding power supplies are designed with this responsiveness in mind.
It is also known to provide the output of an engine-driven generator/alternator as the input to a welding power supply. Welding power supplies that receive a generator/alternator input also include phase controlled rectifiers, convertors (invertors, series resonant convertors, etc.) and transformers with rectifiers. One example of a welding power supply having an engine/generator is the Miller PipePro 304(trademark), which is described in U.S. application Ser. No. 08/858,129, filed May 19, 1997, (hereby incorporated by reference), entitled Engine-driven Invertor With Feedback Control, and assigned to the assignee of this invention.
There are significant power limitations for engine-driven generator welding power supplies. For example, the input power from an engine-driven generator cannot instantly respond to sudden increases in needed input power, because, at least in some instances, the engine may take some time to increase its speed, thus providing the additional needed power. Additionally, it is desirable to cause or allow the engine to idle under some circumstances, so as to enhance fuel economy and reduce wear and tear. Welding power supplies designed for engine-driven generators are typically designed with these concerns in mind.
Engine-driven generator welding power supplies are often portable. Accordingly, they are at times used where utility power is unavailable, (outdoors, e.g.). Other times they are used where utility power or portable generator is available (indoors or near a shop, e.g.). However, because engine-driven generator welding power supplies are not designed for utility input, the engine must still be used to provide power. This may be costly (because engine power often costs more than utility power), noisy, and can create hazardous fumes indoors. Thus, sometimes the user has two welders: an engine-driven welding power supply to be where utility power is not available and a utility powered welding power supply to be used where utility power is available.
Given the expense of welding power supplies, it is desirable for a welding power supply to be capable of being powered by utility power (or some other source of power) and be capable of being powered by an engine-driven generator. Preferably, such a welding power supply will be designed to adequately operate with utility power input and with generator power input, given the different design considerations of the different input powers. Also, such a power supply will preferably be convertible from using one of engine and utility power to the other without having to unplug the power supply, or turn off the engine.
According to a first aspect of the invention a welder includes a power supply having a power supply input and a power output. An input circuit has an engine power input and a utility power input. One of the engine power input and the utility power input is selectively connected to the power supply input in response to a mode select input. An input selector having an engine mode and a utility mode is connected to the mode select input.
The input selector includes a user selectable input, which may be a user switch on a welder control panel, and preferably a three position switch having an engine mode position, a utility mode position and an off position in various alternatives.
The engine/generator has an electrical output connected to the engine power input, and an engine disable input in another embodiment. The input circuit includes a disable output, and the disable output is connected to the disable input when the user switch is in the utility position. The disable input may include a field current cut-off circuit, a starter cut-off circuit, and/or a battery cut-off circuit, responsive to the disable output.
The power supply includes an inverter, chopper, and/or a phase controlled device in various embodiments.
The welder is a single-package, stand-alone, welder, and/or includes an engine/generator having an electrical output connected to the engine power input, and/or an auxiliary power output disposed to derive power from the engine/generator in other embodiments.
The input selector includes a sensor circuit, that senses and is responsive to the presence, absence or other parameter of utility power being provided to the utility power input in another embodiment.
According to a second aspect of the invention a method of providing welding power includes selecting an engine or utility mode, selecting between one of engine power input and utility power as an input power in response to the selected mode;, and converting the input power to welding power.
Selecting an engine or utility mode includes responding to a user selectable input, such as a user switch on a welder control panel, in various alternatives.
The method includes generating electrical power and providing the electrical power as the engine power input, when the engine mode is selected, and or disabling the generated output, for example by disrupting a field current or disrupting battery power, when the utility mode is selected in other alternatives.
Converting the input includes inverting the input or chopping the input in various embodiments.
Selecting an engine or utility mode includes sensing and responding to the presence, absence, or other parameter of utility power being provided to the utility power input and/or engine power input in various alternatives.
Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.